Recent proposals include methods for making conductive substrates using a liquid-based process such as screen printing or an ink jet method. Liquid-based processes require less investment in facilities and use less consumable materials than, for example, ones using vapor deposition of a selected kind of metal, ITO, or the like to form a conductive substrate pattern or those using etching of a copper film or an aluminum film attached to an insulating resin for the same purpose; thus, such processes allow significant reduction of manufacturing cost. However, conductive substrates made using a liquid-based process contain vast amounts of impurities and thus are difficult to produce with a desired conductivity. As solutions to this problem, researchers have proposed many improved conductive inks for liquid-based manufacturing processes; however, all of them are lacking in practicality when seen from the viewpoint of cost-effectiveness